Projector and light source controlling method thereof

ABSTRACT

A projector and a light source controlling method thereof are provided. The light source controlling method includes the following steps. The light source module is controlled to adjust a luminance of a projection light generated by a light source module starting from a low luminance. A power source voltage from an electronic device is detected to be equal to a threshold voltage or not. A power of the power source voltage is detected to be equal to a threshold power or not. When the power source voltage is equal to the threshold voltage and the power of the power source voltage is less than or equal to the threshold power, or when the power source voltage is greater than or equal to the threshold voltage and the power of the power source voltage is equal to the threshold power, the adjustment of the luminance of the projection light is stopped.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of China application serialno. 201110305211.2, filed on Sep. 30, 2011. The entirety of theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an optical device and a light sourcecontrolling method thereof, in particular, to a projector and a lightsource controlling method thereof.

2. Description of Related Art

A projection device can project an image onto a large screen for theconvenience of viewing by lots of people at the same time, so theprojection device is commonly applied in public places like companies orschools. Moreover, in the development trend of the large scale of thehome display products, the projection device is gradually popularized incommon families and becomes an electronic product that is commonly seenin modern lives.

Along with the progress of technology, the portable micro projector(pico projector, or referred to as mini projector) has gradually becomethe mainstream for the future personal digital market. Generallyspeaking, a light source of the micro projector adopts a light emittingdiode (LED) or another solid-state light source. When the microprojector is connected to the electronic device, the voltage provided bythe electronic device serves as the operating voltage of the microprojector.

However, since the micro projector has to use the voltage of theelectronic device, the stability of the internal voltage of theelectronic device is influenced when the micro projector is connected tothe electronic device. When the power of the voltage provided by theelectronic device is relatively low, the abnormal running or even theauto shutdown of the electronic device may be caused when the microprojector is connected to the electronic device. In the situation of theabnormal running and the auto shutdown, the components of the electronicdevice are exposed to the risk of damages.

Taiwan Grant Patent No. 1307808 has disclosed a projection device, inwhich a connector of a power source circuit system is electricallyconnected to a USB connector of a computer by a USB cable, so that thecomputer provides a power source for the projection device. A casing ofthe projection device encapsulates a projection module, a driving moduleand the power source circuit system of the projection device and exposessome connectors of the power source circuit system.

Taiwan Grant Utility Model Patent No. M357153 has disclosed a projectiondevice, which receives a power source and signal sent by a computerthrough a USB interface and a USB cable. The USB interface of theprojection device may be connected to at least one USB interface of thecomputer, so as to receive the power source through the connected USBinterface and receive the signal through one of the connected USBinterface. The voltage of the power source received by the projectiondevice is changed by a voltage control module and then transferred to aswitching module. The switching module transfers the changed voltage toan image display module. The driving module of the projection deviceadjusts the current received by the USB interface from the computer andtransfers the adjusted current to the image display module to change thedisplay brightness of the image display module.

SUMMARY OF THE INVENTION

The invention is directed to a projector and a light source controllingmethod thereof; and the projector and the light source controllingmethod thereof may alleviate the influence on an internal voltage of anelectronic device when the projector is electrically connected to theelectronic device, so as to prevent abnormal running or auto shutdown ofthe electronic device caused by the unstable internal voltage andfurther protect internal components of the electronic device fromdamages.

The objectives and advantages of the invention may be further understoodfrom the technical features disclosed in the invention.

To achieve one, some or all of the above objectives or other objectives,in an embodiment of the invention, a projector electrically connected toan electronic device is provided. The projector includes a detectionunit, a projection unit, a light source module, and a control unit. Thedetection unit detects whether a power source voltage from theelectronic device is equal to the threshold voltage and detects whethera power of the power source voltage is equal to a threshold power, andoutputs a detection result. The projection unit receives an image dataand a projection light to project an image. The light source moduleprovides the projection light. The control unit is electricallyconnected to the detection unit, the projection unit, and the lightsource module. The control unit receives an image signal from theelectronic device and generates the image data received by theprojection unit, and controls the light source module to adjust aluminance of the projection light starting from a low luminance. Whenthe detection result shows that the power source voltage is equal to thethreshold voltage and the power of the power source voltage is less thanor equal to the threshold power, or when the detection result shows thatthe power source voltage is greater than or equal to the thresholdvoltage and the power of the power source voltage is equal to thethreshold power, the adjustment of the luminance of the projection lightis stopped.

In another embodiment of the invention, a light source controllingmethod of a projector is provided. The projector includes a light sourcemodule. The light source controlling method includes the followingsteps. The light source module is controlled to adjust a luminance of aprojection light generated by the light source module starting from alow luminance. A power source voltage from an electronic device isdetected to be equal to a threshold voltage or not. A power of the powersource voltage is detected to be equal to the threshold power or not.When the power source voltage is equal to the threshold voltage and thepower of the power source voltage is less than or equal to the thresholdpower, or when the power source voltage is greater than or equal to thethreshold voltage and the power of the power source voltage is equal tothe threshold power, the adjustment of the luminance of the projectionlight is stopped.

In view of the above, in the projector and the light source controllingmethod thereof according to an embodiment of the invention, the lightsource module adjusts the luminance of the projection light startingfrom the low luminance, which may reduce the influence on the internalvoltage of the electronic device when the projector is connected to theelectronic device to the lowest level, so as to prevent the abnormalrunning or auto shutdown of the electronic device caused by the unstableinternal voltage and further protect internal components of theelectronic device from damages.

Other objectives, features and advantages of the invention will befurther understood from the further technological features disclosed bythe embodiments of the invention wherein there are shown and describedpreferred embodiments of the invention, simply by way of illustration ofmodes best suited to carry out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a systematic schematic view of a projector electricallyconnected to an electronic device according to an embodiment of theinvention.

FIG. 2 is a flow chart of a light source controlling method of aprojector according to an embodiment of the invention.

DESCRIPTION OF THE EMBODIMENTS

It is to be understood that other embodiment may be utilized andstructural changes may be made without departing from the scope of thepresent invention. Also, it is to be understood that the phraseology andterminology used herein are for the purpose of description and shouldnot be regarded as limiting. The use of “including,” “comprising,” or“having” and variations thereof herein is meant to encompass the itemslisted thereafter and equivalents thereof as well as additional items.Unless limited otherwise, the terms “connected,” “coupled,” and“mounted,” and variations thereof herein are used broadly and encompassdirect and indirect connections, couplings, and mountings.

In the embodiment, the projector 100 includes a connection port 110, acontrol unit 120, a light source module 130, a detection unit 140, aprojection unit 150, and a power source supply unit 160. The connectionport 110 is used to connect an electronic device 10, so as to receive apower source voltage Vp and an image signal Sim from the electronicdevice 10. The connection port 110 may be a Universal Serial Bus (USB)port so as to be electrically connected to at least one USB port of theelectronic device 10. The electronic device 10 may be the electronicdevice with an audio-visual playback function, for example, a videoplayer or a computer device.

The detection unit 140 is electrically connected to the connection port110, for detecting whether the power source voltage Vp from theelectronic device 10 is equal to a threshold voltage, and detectingwhether a power of the power source voltage Vp is equal to the thresholdpower, and outputting a detection result DRT. The power source voltageVp may be directly measured, and the power of the power source voltageVp may be obtained by calculating the measured power source voltage Vpand the measured current. An analog-to-digital converter (ADC) isconfigured in the detection unit 140, for converting the detectedvoltage and current into digital data for the convenience of calculationand comparison.

The power source voltage Vp of the electronic device 10 decreasesdepending on the increasing of the luminance output by the light sourcemodule 130 of the projector 100. In the embodiment of the invention, thethreshold voltage is set to be 0.9 times a standard value of the powersource voltage Vp, and the threshold power is set to be twice as big asa rated power of a single USB port. Furthermore, if the connection port110 is the connection port conforming to the USB 2.0, for example, sincethe USB 2.0 specifies the rated output voltage (i.e. the standard valueof the power source voltage Vp) of the connection port is 5 V and therated output current is 700 mA, the threshold voltage may be 4.5 V (i.e.5 V×0.9), the rated power of the connection port 110 is 3.5 W (i.e. 5V×700 mA), the threshold power may be 7 W (i.e. 2×3.5 W). If theconnection port 110 is the connection port conforming to the USB 3.0,since the USB 3.0 specifies the rated output voltage of the connectionport is 5 V and the rated output current is 900 mA, the thresholdvoltage may be 4.5 V (i.e. 5×0.9 V), the rated power of the connectionport 110 is 4.5 W (i.e. 5×900 mA), the threshold power may be 9 W (i.e.2×4.5 W). However, the threshold voltage and the threshold power may bedetermined according to the actual electrical characteristics of theconnection port of the electronic device 10 connected to the connectionport 110, and is not limited to the embodiment of the invention.

The control unit 120 is electrically connected to the connection port110, the detection unit 140, and the light source module 130. Thecontrol unit 120 receives the image signal Sim from the electronicdevice 10 and generates an image data Dim according to the image signalSim. The control unit 120 controls the light source module 130 toprovide a projection light PL, and controls the light source module 130to adjust the luminance of the projection light PL starting from the lowluminance. A light-emitting component (e.g. Light Emitting Diode, LED)may be configured in the light source module 130 to generate theprojection light PL. The aforementioned low luminance may be the minimumluminance of the projection light PL generated by the light sourcemodule 130, or the aforementioned low luminance may be a lumen of thelowest start luminance of the LED, for example, 3-5 lumens for a redLED, 19-20 lumens for a green LED, and 0.5-0.7 lumens for a blue LED. Inan exemplary embodiment, the red LED is 3.7 lumens, the green LED is19.4 lumens, and the blue LED is 0.6 lumens, but the invention is notlimited to this above-mentioned.

The projection unit 150 is electrically connected to the control unit120, for receiving the image data Dim and the projection light PL toproject an image 20. The power source supply unit 160 is electricallyconnected to the connection port 110, the control unit 120, the lightsource module 130, the detection unit 140, and the projection unit 150,for receiving the power source voltage Vp to generate a operatingvoltage Vcc required by the control unit 120, the light source module130, the detection unit 140, and the projection unit 150 while runningThe operating voltage Vcc may be provided to the control unit 120, thelight source module 130, the detection unit 140, and the projection unit150.

The control unit 120 may control the light source module 130 to adjustthe luminance of the projection light PL according to the detectionresult DRT. In details, when the detection result DRT shows that thepower source voltage Vp is greater than the threshold voltage and thepower of the power source voltage Vp is less than the threshold power,the control unit 120 controls the light source module 130 to increasethe luminance of the projection light PL. When the detection result DRTshows that the power source voltage Vp is greater than the thresholdvoltage and the power of the power source voltage Vp is greater than thethreshold power, the control unit 120 controls the light source module130 to reduce the luminance of the projection light PL. When thedetection result DRT shows that the power source voltage Vp is less thanthe threshold voltage and the power of the power source voltage Vp isless than the threshold power, the control unit 120 controls the lightsource module 130 to reduce the luminance of the projection light PL.When the detection result DRT shows that the power source voltage Vp isless than the threshold voltage and the power of the power sourcevoltage Vp is greater than the threshold power, the control unit 120controls the light source module 130 to reduce the luminance of theprojection light PL.

When the detection result DRT shows that the power source voltage Vp isequal to the threshold voltage and the power of the power source voltageVp is less than or equal to the threshold power or the power sourcevoltage Vp is greater than or equal to the threshold voltage and thepower of the power source voltage Vp is equal to the threshold power,the control unit 120 controls the light source module 130 to stop theadjustment of the luminance of the projection light PL.

Generally speaking, the high power consumption part of the projector 100is the light source module 130 that provides the projection light PL. Inthe embodiment, since the light source module 130 adjusts the luminanceof the projection light PL starting from the low luminance, when theprojector 100 is connected to the electronic device 10 and extracts thepower source voltage Vp of the electronic device 10, the influence onthe internal voltage of the electronic device 10 may be reduced to thelowest level, so as to prevent the abnormal running or even the autoshutdown of the electronic device 10 caused by the unstable internalvoltage and further protect the components in the electronic device 10from damages. The control unit 120 adjusts the power consumption of theprojector 100 by means of adjusting the luminance of the projectionlight PL, and determines whether the power consumption of the projector100 causes an excessive loading on the electronic device 10 by means ofdetecting whether the power source voltage Vp is equal to the thresholdvoltage and detecting whether the power of the power source voltage Vpis equal to the threshold power. In the manner, the power consumption ofthe projector 100 is adjusted to an appropriate range.

According to the above description, a light source controlling method ofa projector may be provided, which is applicable to the projector 100.Referring to FIG. 2, in the embodiment, the projector includes a lightsource module. Firstly, the light source module is controlled to adjusta luminance of a projection light generated by the light source modulefrom a low luminance (step S210). Subsequently, a power source voltagefrom the electronic device Vp is detected to be equal to a thresholdvoltage Vth or not and a power Pp of the power source voltage Vp isdetected to be equal to a threshold power Pth or not (step S220). Whenthe power source voltage Vp is greater than the threshold voltage Vthand the power Pp of the power source voltage Vp is less than thethreshold power Pth, the luminance of the projection light is increased(step S230).

When the power source voltage Vp is equal to the threshold voltage Vthand the power Pp of the power source voltage Vp is less than or equal tothe threshold power Pth, or when the power source voltage Vp is greaterthan or equal to the threshold voltage Vth and the power Pp of the powersource voltage Vp is equal to the threshold power Pth, the adjustment ofthe luminance of the projection light is stopped (step S240). When thepower source voltage Vp is greater than the threshold voltage Vth andthe power Pp of the power source voltage Vp is greater than thethreshold power Pth, when power source voltage Vp is less than thethreshold voltage Vth and the power Pp of the power source voltage Vp isless than the threshold power Pth, or the power source voltage Vp isless than the threshold voltage Vth and the power Pp of the power sourcevoltage Vp is greater than the threshold power Pth, the luminance of theprojection light is reduced (step S250). After the steps S230, S240, andS250 are finished, the process returns to the step S220 to detectwhether the adjusted power source voltage Vp and adjusted the power Ppof the power source voltage Vp falls in the appropriate range or thepower source voltage Vp and whether the power Pp of the power sourcevoltage Vp is maintained in the appropriate range. The details of theabove steps may refer to the abovementioned relevant descriptions andFIG. 1, so the details will not be repeated herein.

In view of the above, in the projector and the light source controllingmethod thereof according to an embodiment of the invention, the lightsource module adjusts the luminance of the projection light from the lowluminance, which may reduce the influence on the internal voltage of theelectronic device when the projector is connected to the electronicdevice and extracts the power source voltage of the electronic device tothe lowest level, so as to prevent the abnormal running or even the autoshutdown of the electronic device caused by the unstable internalvoltage and further protect the internal components of the electronicdevice from damages. The control unit adjusts the power consumption ofthe projector by means of adjusting the luminance of the projectionlight and determines whether the power consumption of the projectorcauses an excessive loading on the electronic device by means ofdetecting whether the power source voltage is equal to the thresholdvoltage and detecting whether the power of the power source voltage isequal to the threshold power. In the manner, the power consumption ofthe projector is adjusted to an appropriate range.

The foregoing description of the preferred embodiments of the inventionhas been presented for purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform or to exemplary embodiments disclosed. Accordingly, the foregoingdescription should be regarded as illustrative rather than restrictive.Obviously, many modifications and variations will be apparent topractitioners skilled in this art. The embodiments are chosen anddescribed in order to best explain the principles of the invention andits best mode practical application, thereby to enable persons skilledin the art to understand the invention for various embodiments and withvarious modifications as are suited to the particular use orimplementation contemplated. It is intended that the scope of theinvention be defined by the claims appended hereto and their equivalentsin which all terms are meant in their broadest reasonable sense unlessotherwise indicated. Therefore, the term “the invention”, “the presentinvention” or the like does not necessarily limit the claim scope to aspecific embodiment, and the reference to particularly preferredexemplary embodiments of the invention does not imply a limitation onthe invention, and no such limitation is to be inferred. The inventionis limited only by the spirit and scope of the appended claims. Theabstract of the disclosure is provided to comply with the rulesrequiring an abstract, which will allow a searcher to quickly ascertainthe subject matter of the technical disclosure of any patent issued fromthis disclosure. It is submitted with the understanding that it will notbe used to interpret or limit the scope or meaning of the claims. Anyadvantages and benefits described may not apply to all embodiments ofthe invention. It should be appreciated that variations may be made inthe embodiments described by persons skilled in the art withoutdeparting from the scope of the present invention as defined by thefollowing claims. Moreover, no element and component in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element or component is explicitly recited in the followingclaims.

What is claimed is:
 1. A projector electrically connected to anelectronic device, the projector comprising: a detection unit, fordetecting whether a power source voltage from the electronic device isequal to a threshold voltage, detecting whether a power of the powersource voltage is equal to a threshold power, and outputting a detectionresult; a light source module, for providing a projection light; aprojection unit, for receiving an image data and the projection light toproject an image; and a control unit, electrically connected to thedetection unit, the projection unit and the light source module, forreceiving an image signal from the electronic device and generating theimage data received by the projection unit, wherein the control unitcontrols the light source module to adjust a luminance of the projectionlight starting from a low luminance, and stops the adjustment of theluminance of the projection light when the detection result shows thatthe power source voltage is equal to the threshold voltage and the powerof the power source voltage is less than or equal to the thresholdpower, or when the detection result shows that the power source voltageis greater than or equal to the threshold voltage and the power of thepower source voltage is equal to the threshold power.
 2. The projectoraccording to claim 1, wherein when the power source voltage is greaterthan the threshold voltage and the power of the power source voltage isless than the threshold power, the control unit controls the lightsource module to increase the luminance of the projection light; whenthe power source voltage is greater than the threshold voltage and thepower of the power source voltage is greater than the threshold power,the control unit controls the light source module to reduce theluminance of the projection light; when the power source voltage is lessthan the threshold voltage and the power of the power source voltage isless than the threshold power, the control unit controls the lightsource module to reduce the luminance of the projection light; and whenthe power source voltage is less than the threshold voltage and thepower of the power source voltage is greater than the threshold power,the control unit controls the light source module to reduce theluminance of the projection light.
 3. The projector according to claim1, wherein the low luminance is a minimum luminance of the projectionlight generated by the light source module.
 4. The projector accordingto claim 1, further comprising a power source supply unit electricallyconnected to the detection unit, the projection unit, the light sourcemodule, and the control unit, for receiving the power source voltagegenerated an operating voltage, wherein the operating voltage isprovided to the detection unit, the projection unit, the light sourcemodule, and the control unit.
 5. The projector according to claim 1,wherein the threshold voltage is 0.9 times a standard value of the powersource voltage.
 6. The projector according to claim 1, wherein theprojector is electrically connected to at least one Universal Serial Busport of the electronic device.
 7. The projector according to claim 6,wherein the threshold power is two times a rated power of a singleUniversal Serial Bus port.
 8. A light source controlling method of aprojector, wherein the projector comprises a light source module, thelight source controlling method comprising: controlling the light sourcemodule to adjust a luminance of a projection light generated by thelight source module starting from a low luminance; detecting whether apower source voltage from the electronic device is equal to a thresholdvoltage; detecting whether a power of the power source voltage is equalto a threshold power; and stopping the adjustment of the luminance ofthe projection light when the power source voltage is equal to thethreshold voltage and the power of the power source voltage is less thanor equal to the threshold power, or when the power source voltage isgreater than or equal to the threshold voltage and the power of thepower source voltage is equal to the threshold power.
 9. The lightsource controlling method of the projector according to claim 8, whereinthe step of adjusting the luminance of the projection light generated bythe light source module comprises: increasing the luminance of theprojection light when the power source voltage is greater than thethreshold voltage and the power of the power source voltage is less thanthe threshold power; reducing the luminance of the projection light whenthe power source voltage is greater than the threshold voltage and thepower of the power source voltage is greater than the threshold power;reducing the luminance of the projection light when the power sourcevoltage is less than the threshold voltage and the power of the powersource voltage is less than the threshold power; and reducing theluminance of the projection light when the power source voltage is lessthan the threshold voltage and the power of the power source voltage isgreater than the threshold power.
 10. The light source controllingmethod of the projector according to claim 8, wherein the low luminanceis defined as a minimum luminance of the projection light generated bythe light source module.
 11. The light source controlling method of theprojector according to claim 8, wherein the threshold voltage is 0.9times a standard value of the power source voltage.
 12. The light sourcecontrolling method of the projector according to claim 8, wherein thethreshold power is twice a rated power of a Universal Serial Bus port.